Tailings Storage Facility Operations, Maintenance and Surveillance Manual Oyu Tolgoi LLC
Oyu Tolgoi LLC Tailings Storage Facility Operations, Maintenance and Surveillance Manual Page 1 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 1 Document Number: TSF-001 Rev: 2 PURPOSE This Operation, Maintenance, and Surveillance (OMS) manual has been prepared for the Tailings Storage Facility (TSF) at the Oyu Tolgoi Copper mine, Mongolia, and acts as a reference document for the facility’s operation, maintenance, and surveillance. Oyu Tolgoi LLC (OT) Concentrator operations personnel, Rio Tinto Technology and Innovation (T&I) and Klohn Crippen Berger (KCB), the facility’s designers, have provided input to this manual. 2 OBJECTIVES The objective of the OMS manual is to define and describe: 3 Roles and responsibilities of personnel assigned to the facility. Procedures and processes for managing change. The key components of the facility. Including threshold values, construction plan and QC, permit requirements and associated regulatory agencies. Procedures required for operating, monitoring the performance of, and maintaining the facility to ensure that it functions in accordance with its design, meets regulatory and corporate policy obligations, and links to emergency planning and response. Requirements for analysis and documentation of the performance of the facility so that this information can be used to update the design. A bibliography of relative design documents pertinent to the TSF operation. Meet the requirements of forthcoming Rio Tinto Standards for OMS of Tailings Storage Facilities. REGULATORY REQUIREMENTS 3.1 Regulatory Agencies Environmental Certification - State Specialized Inspection Agency (SSIA) Geology and Mining Compliance – General Agency for Specialised Inspection (GASI) 3.2 Regulatory Approval Mongolian Government – Energy, Mines and Resources. Environmental Certification - State Specialized Inspection Agency (SSIA) Geology and Mining Compliance – General Agency for Specialised Inspection (GASI) 3.3 4 Regulatory Requirements Environmental Certification - State Specialized Inspection Agency (SSIA) Geology and Mining Compliance – General Agency for Specialised Inspection (GASI) ROLES AND RESPONSIBILITIES Page 2 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 4.1 Document Number: TSF-001 Rev: 2 Organization, Structure, and Individual Responsibilities The operation, maintenance, surveillance or emergency preparedness and response of the TSF are the responsibility of the Tailings Management Team (TMT). This team comprises individuals from OT and KCB. Oyu Tolgoi is the lead coordinator of the OMS manual and is ultimately responsible to ensure all aspects of the TSF manual are met. KCB is the facility’s Engineer of record. Periodic technical reviews (Independent Technical Review Boards) may be commissioned to review the design and provide updates based on the actual performance. Independent oversight may also be conducted by representatives of Rio Tinto Technology and Innovation (T&I). Designated personnel within the TMT, along with their position and responsibilities, are summarized in Table 1. Table 1 Designated Personnel for TMT Position Personnel and Contact Information Responsibilities General Manager Concentrator Andrew Miller Reports to Chief Operations Officer. General Manager – Open Pit Paul Douglas Overall Operations and Maintenace review and implementation, and budget allocation for TSF operations and maintenance. Acting in the GM role. Reports to Chief Operations Officer. Provision of TSF Construction capability and budget allocation for TSF Construction. Principal Adviser Geotechnical Joergen Pilz Rio Tinto Group coordinator of TSF, project review and implementation. Technical support and review of TSF monitoring at OT site. Manager Mine Operations – Open Pit Morris Dzus Reports to GM Open Pit Manages Open Pit Mine Operations. Executes the Mine Plan; which includes TSF Construction Plan. Page 3 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Manager Technical Services – Open Pit Document Number: TSF-001 Binsar Sirait Rev: 2 Reports to GM Open Pit Manages Open Pit Technical Services. Produces the Mine Plan; which includes TSF Construction Plan. Custodian of TSF Permit and License. Manager Concentrator Operations Adrian Zarantonello Superintendent Tailings Operations and Maintenance Clem Turner Reports to GM Concentrator. Manages Concentrator Operations. Reports to GM Concentrator. Assures the safety, conformance, performance and survivability of TSF civil works comprising Mechanical and Electrical systems in support of whole of Concentrator department operations, including: TSF water balance. Reclaim barge. Seepage Collection Pump Station Tailings Pipeline and seepage inspections of diversion ditches. Custodian TSF Risk Assessment. Superintendent TSF Construction Scott Ingram Custodian of the OMS Manual. Reports to Manager Open Pit. Oversight of day to day TSF impoundment construction and maintenance. Including: Construction planning: o Short term. o Long term. Superintendent Concentrator Operations Jody Squires Reports to Manager Concentrator Operations. Mike Evans Oversight of pumping and conveyance of tailings slurry to TSF. Tailings discharge (Slurry Density and Volumes). Page 4 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Supervisor TSF Operations and Maintenance. Document Number: TSF-001 Tsogjavkhlan Sodnomdarjaa Rev: 2 Reports to Superintendent Tailings Operations and Maintenance. Supervise and oversee daily activities of the TSF Operations and Maintenance team. Verify and validate technical compliance of the TSF and Tailing’s Operations and Maintenance team competencies. Coordination of TSF Team Training requirements. Tailings Engineer Odkhuu Tsogtbaatar Reports to Manager Open Pit Technical Services. Routine inspections for quality assurance and quality control, data collection, surveying, providing planning direction to Superintendent TSF Construction. Including: Supervisor TSF Construction Munkh-Erdene Amarsanaa; Bat-Amgalan Sangaa; QC reporting. QC database management. Survey records. Instrumentation readings. Instrumentation databases. Reports to Superintendent TSF Construction. Nasanbuyan Tserenbat; Day to day supervision of haul, placement, and compaction of tailings in TSF, general operations and maintenance of the TSF impoundment. Engineer of Record and Geotechnical Consultant, KCB Howard Plewes Consultant under Contract. Design Authority Project Manager, KCB Pam Fines Periodic inspections for quality assurance, annual compliance reporting, geotechnical analysis and risk management of ongoing construction, instrumentation data review. Reports to Engineer of Record and Geotechnical Consultant. Consultant under Contract. Project Manages the on-shore and off-shore QA/QC requirement for TSF Construction. Page 5 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Principle Advisor Environment Document Number: TSF-001 Mark Newby Rev: 2 Reports to General Manager HSE. Verification and Validation of permitting requirements. Government reporting. Principle Advisor Water PAF/NAF classification/compliance. Reports to General Manager HSE. Mark Newby Permitting requirements, annual environmental reports, water quality and level monitoring. Superintendent Safety Concentrator Bat-Erdene Dambadarjaa Independent Technical Review Board Various preeminent specialists in the field of TSF and Dam construction. Ground Water sampling. Reports to GM Concentrator. Verify and validate training requirements and job hazard analysis are completed as required. Consultant under contract. Commissioned as deemed necessary to effect periodic technical reviews of design and to provide advice on actual TSF system performance. Responsibility of the TMT and the ongoing operation, monitoring, maintenance, and surveillance of the TSF falls under the General Manager Concentrator for TSF Operations and Maintenance and the General Manager Open Pit for TSF Construction. Furthermore, for their respective areas of responsibility, both General Manager’s must ensure adequate resources (both financial and staff) are made available to ensure the safe, sensible and compliant operation of the TSF. Change management at the TSF must be prioritised and scheduled with the knowledge of the TMT. Major design changes or opportunities must be identified by the TMT so that these can be assessed by the Engineer of Record and independently reviewed. The OT Change Management system will be applied and change recorded and approved via the on-line change management system, located at http://otmoc/ . Further templates and policy guidance is located at http://otportal/HSE/Management%20of%20change/SitePages/home.aspx . 4.2 Competency and Training Appropriate training programs are required for all personnel involved in the operation, maintenance, and surveillance of the TSF, including all its components. The Superintendent Tailings Operation and Maintenance, Superintendent TSF Construction are required to fully understand and implement the operation, maintenance, and surveillance requirements of the TSF, and ensure the design criteria for the facility is verified and validated. This is achieved through consultation with the Engineer of Record. Page 6 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 All personnel working at the TSF are to have an appropriate understanding of the OMS manual and their respective roles and responsibilities. Relevant procedures include: OT Emergency Procedures, OT Spill Response Plan, TSF Embankment Failure Prevention Plan, and TSF Emergency Preparedness Plan. It is the role of the specific supervisor of the personnel to ensure that training is accomplished and documented. As well as understanding of the OMS manual, all TSF personnel are responsible for continually being alert to visual cues regarding facility performance. Anything observed to be outside of normal operating parameters, as outlined in this manual, must be reported immediately to the Manager Mine Operations and Manager Concentrator Operations. 5 OMS MANUAL CONTROL AND UPDATE This OMS manual is a controlled document, with specified procedures for: 5.1 Distributing, removing and archiving out‐of‐date materials; Filing the manual and supporting documents; and Reviewing and updating the manual. Distribution of Material A hard copy of the OMS manual will be held by the Superintendent Tailings Operations and Maintenance. Electronic copies will be available online at the OT Portal within the Concentrator department portal, http://otportal/concentrator/sitepages/home.aspx. Additional copies are to be submitted to regulatory agencies, as required. The Superintendent Tailings Operations and Maintenance is responsible for the management of change of OMS manual. Any requests for copies are to be made to the Superintendent Tailings Operations and Maintenance who will have that name added to the distribution list, providing a numbered copy for the user, and in doing so, ensure the recipient receives ongoing updates. No other copies (of copies) are to be made. Out‐of‐date TSF materials are to be archived by the Superintendent Tailings Operations and Maintenance. Out‐of‐date copies of the OMS manual are to be collected by the Superintendent Tailings Operations and Maintenance and destroyed. Several copies of the most recently superseded versions are to be archived in secure storage as required for legal purposes. 5.2 Manual and Supporting Document Location The original copy of the OMS manual along with the following supporting documents will be stored electronically on the Concentrator Tailings section of the OT server, http://otportal/concentrator/sitepages/home.aspx, and in the Superintendent Tailings Operations and Maintenance office on site. These documents are maintained and under the control of the Superintendent Tailings Operations and Maintenance. Page 7 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 The following items shall be covered or referenced in the filing system: Operation, Maintenance, and Surveillance Manual. As built drawings from original construction and all subsequent construction phases. Construction records including performance and construction plans. All IFC documents including both original design data and all modifications or revisions. All inspections, QC/QA documentation and annual reviews. Photographic records. Correspondence with Engineer of Record and Geotechnical Consultants with relevant supporting information. Correspondence with Regulatory Agencies complete with records of compliance and details of any remedial action. Copies of independent technical reviews and their findings (ITRB documentation) Along with the above referenced documents, the following specific reports dealing with the TSF will be stored in the Superintendent Tailings Operations and Maintenance office, on site. Emergency Planning Documents Oyu Tolgoi Environmental Monitoring Plan. Oyu Tolgoi Spill Contingency Plan. MSDS documentation for any material used within the TSF. TSF Approval Documents A letter by Mongolian Government – Energy, Mines and Resources entitled, “Approval of Oyu Tolgoi Tailings Management Plan”. Design Reports The principal design document: “Oyu Tolgoi Project – Tailings Storage Facility 2010 Feasibility Study Update, “ August 5, 2011. [Includes original starter dike specifications and drawings.” A report by KCB entitled, “Tailings Storage Facility Design Summary for Detail Design Review (Rev.3) – Oyu Tolgoi Project, Mongolia”, dated 3 May 2011. A letter by KCB entitled, “Final Preliminary Design – Tailings Storage Facility”. Updated specifications by KCB. Hydrology Report. Environmental Characterization of Samples. Monitoring Documents A letter by KCB entitled, “Tailings Storage Facility – Foundation Movement Monitoring Update”. A technical memo by KCB entitled, “Tailings Storage Facility – Instrumentation Data Update”. Page 8 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Construction Reviews A technical memo by KCB entitled, “Review of Compaction and Moisture Content at the Tailings Storage Facility Mill Moisture”. A technical memo by KCB entitled, Review of Reduced Trafficability and Compaction with High Mill Moisture Content to the Tailings Storage Facility Mill moisture. A report by KCB entitled “Review of TSF Surface Water Diversion Berms and Ditches”. A letter by KCB entitled, “Tailings Storage Facility – Interim As‐ built Construction Report”. Tailings Risk Management Assessment A report by KCB entitled “Tailings Risk Assessment Oyu Tolgoi Project”. 5.3 Reviewing and Updating the Manual This manual is an update of operations, experience, and drafts completed since planning for the OT TSF commenced in 2007, and in its current form will be referred to as Revision 2012‐ 1. This manual will be updated every five years or after any significant change to personnel, operations, or design criteria. TSF design will be reviewed annually with an external design review every 5 years. An OMS manual will be in place through the full life cycle of the TSF including the end of the operating phase, into decommissioning and closure. Annual TSF management system reviews are to include an evaluation of this OMS manual. 6 MANAGING CHANGE TSF Change management will be in concert with Element 11 (Management of Change) of the Rio Tinto Health, Safety, Environment and Quality (HSEQ) Management System Standard. Flowchart 1 reveals the TSF change management process. Details of the Standard and associated templates are located on the OT intranet at: http://otportal/HSE/Management%20of%20change/SitePages/home.aspx . Page 9 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Identify change Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Conduct an emergency change Aspect of business requiring change Employee / contractor identifies change Change required immediately (emergency change)? YES Develop an emergency change plan Assess hazards and identify controls NO Obtain proposal approval Develop proposal for change Obtain authorisation Assess nature of change / risks to determine appropriate tools & techniques for risk analysis Identify a Change Proposer Describe the change Implement change Assess the risk and identify controls Identify impacted stakeholders Develop a change proposal Conduct postimplementation review YES Close the change Further assessment required? NO Change Proposal approved? NO Identify the Change Approver Implement the change YES Develop Implementation Plan Identify a Change Implementer Implementation Plan authorised? Implement the change YES Close the change Further assessment required? NO NO NO Review the implementation YES Retrospectively implement the full management of change process Conduct postimplementation review Outcomes of postimplementation approved? Send post implementation notification YES Conduct further assessment Outcomes of implementation approved? Conduct implementation review / pre-acceptance checks YES Change completed Figure 1 Flowchart TSF Change Management Process 7 7.1 FACILITY DESIGN DESCRIPTION Ultimate Facility Overview The ultimate TSF is located east of the Oyu Tolgoi open pit and consists of two adjacent square containment cells (refer to drawing). Embankments will be constructed using mine waste over the mine life and remain post-closure. The 2 cells will share a common central embankment. (Refer to the attached drawings D-6001 and D-6002 for a general arrangement plan of the facilities). Page 10 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Figure 2 TSF Site Plan Cells 1 and 2 of the Tailings Storage Facility (TSF), with the current ultimate crest level of the tailings embankments, will have a combined capacity to store 720 Mt of tailings (equivalent to 740 Mt of milled ore) to accommodate the current 15-year mine plan. Two similar sized cells may be constructed to the east of Cells 1 and 2 to provide additional storage capacity for 1.4 B tons tailings capacity. 7.2 Facility Components The TSF comprises the following components: 7.3 Splitter Dykes. Water Return Pipeline. Water Return Pump Station. Reclaim Pond. Reclaim Barge. Seepage Collection Ditch. Freshwater Diversion Ditch. Toe Collection Pond. East Toe Collection System. Emergency Spillway. Basis of Design and Design Criteria Page 11 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 The design basis may be found in the August 4, 2011 KCB design report and appendices. Specifically, design criteria may be found beginning on page 97 of said report. 7.4 Site Conditions 7.4.1 General Surficial Geology The foundation soils in the TSF area were characterized by extensive field investigations including 85 boreholes, 150 test pits, 60 standpipe piezometer installations, 37 cone penetration tests, 14 seismic cone penetration tests and measurements along 7 kilometres of geophysics lines (see drawing D-6003). The foundation consists of three main units (from top to bottom): fluvial and Aeolian deposits; Cretaceous clay; and residual soils and weathered bedrock. The Cretaceous clay unit controls embankment stability due to its low shear strength, thickness and potential for development of excess pore pressure under loading, which adversely impacts embankment stability. Beneficially, Cretaceous clay has a low permeability, and provides a natural barrier against seepage losses from the impoundment. In areas where the Cretaceous clay is absent, a blanket of compacted Cretaceous clay will be placed on the foundation to form this seepage barrier. 7.4.2 Surface Features Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.4.3 Subsurface Conditions Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.4.4 Groundwater Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.4.5 Permafrost Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.4.6 Bedrock Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.5 Climate and Hydrology Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.6 Seismicity Pore pressures controls the design of the embankments and therefore seismic hazard assessment was completed by the Research Centre of Astronomy and Geophysics of Mongolia (RCAG) and KCB as part of the design scope. RCAG identified two known active geologic faults Page 12 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 in the region; the Tavan Takhil fault located approximately 18 km from site, and the Borzon fault at 120 km distance. These faults are believed capable of generating magnitude M7 earthquakes. The Tavan Takhil fault is the most critical because of its nearness to the site. RCAG estimates a return period of 2250 years for the M7 earthquake. A deterministic seismic hazard assessment (DSHA) was conducted by KCB to establish Maximum Credible Earthquake (MCE) ground motions. Based on this assessment, MCE acceleration with a Peak Ground Acceleration (PGA) of 0.32 g for an M7 earthquake on the Tavan Takhil Fault was selected for embankment design. A set of ten time-histories from past earthquakes satisfying appropriate selection criteria was chosen and modified to match the MCE target spectrum. These modified time-histories were used in the seismic deformation analyses and design of the TSF. 7.7 Tailings Characteristics 7.7.1 Tailings Production The life of mine plan during the design indicated that the total production of tailings would be in the order of 2.2M tonnes during the first 5 years. The anticipated tailings production by year (based on the 2010 OT mine plan) is presented in Table 2. Table 2 Anticipated Tailings Production Projected Tailings Production Year 1 Year 2 Year 3 Year 4 Year 5 Total 7.7.2 Cell 1 (tonnes) 220,988 835,432 357,895 354,140 382,999 2,151,454 Tailings Characterisation The tailings compose of non-plastic fine sand and silt, with approximately 60% silt content. To enhance conservation of water, the tailings will be thickened using a conventional thickener prior to being pumped to the facility for deposition at 60 to 64% solids by weight. Laboratory jar settling tests indicate that the tailings density could approach approximately 72% solid density within several days under self-weight, equivalent to a dry solids density of about 1.35 t/m3. Additional consolidation due to drying and subsequent placements of tailings will further increase the density. In recognition of the potential for changes in tailings composition and segregation, conservative densities of 1.4 t/m3 for starter embankment sizing and 1.5 t/m3 for the ultimate embankment sizing were used. Tailings beach slopes could vary from 0.4% to 2.5% depending on location, actual solids content and rate of deposition. Based on experience with other tailings storage facilities with similar tailings characteristics, an overall beach slope of 1% was used in sizing of the impoundment. A conservative approach was taken in sizing the Cell 1 starter embankment to allow for a range of potential beach slopes between 0.75% and 1.5%. Note: Actual tailings beach slopes must be measured in the field and appropriate annual adjustments in embankment heights made to account for the realized beach slope. Page 13 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Evaporation tests indicate that the tailings surface dries to a hard, dust resistant crust. However, if the crust does not form to the extent predicted, the tailings spigot location will be changed frequently to ensure the beaches remain wet to suppress dust. Observations of crust formation will be made and documented on inactive sub-cells. A supplemental study is being effected to better understand crust formation behaviour. 7.7.3 Acid Generation Potential Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 7.7.4 Dusting Potential Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. 8 8.1 CONSTRUCTION HISTORY Design Criteria based on QA and QC program Refer to KCB Feasibility Study design report located at: http://otportal/concentrator/sitepages/home.aspx. The tailings embankment design considers foundation conditions, fill properties, tailings deposition sequence, and water management requirements. Design seismic loading was applied to the design of all sections. Both non-acid forming (NAF) and potentially acid forming (PAF) waste rock may be used for construction of the main embankment shell. Note: PAF rock can only be placed in select locations where the likelihood of contact with water or seepage solutions is minimal. The Canadian Dam Association “Dam Safety Guidelines” (CDA, 2007) were selected to provide appropriate design basis for seismic loading, flood protection, and embankment stability safety factors, based on consequence of failure of the containment embankments. Consequence is assessed in terms of incremental losses of: life, environmental, cultural, infrastructure and economic. On the basis of consequence of failure, dams are classified as “low”, “significant”, “high”, “very high” or “extreme”. The higher the dam classification, the greater the seismic and flood design requirements. The Oyu Tolgoi TSF is classified as a “very high” consequence structure in consideration of the economic, social and environmental consequences of failure. Flood and seismic criteria for the TSF design have therefore been selected to meet or exceed CDA guidelines. The Starter Embankment is designed for “high” consequence criteria in consideration of the limited height and short life of the structure. The TSF perimeter has been divided into three embankment design sections: the wet section, the dry section, and the reclaim section; based on the degree of tailings saturation and the likelihood that water will pond against the upstream slope of the embankment. Since a pond will be maintained in the reclaim section, that portion of the embankment will include a zone of low permeability compacted clay and will be raised in the downstream direction. The wet section, along the East embankment where wet tailings may rest against the embankment, will be raised using the centreline method. The dry section embankments will be Page 14 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 raised using a modified centreline method, taking advantage of drier, stronger tailings to reduce fill volumes. All sections will include a filter zone of NAF Oxide material between the tailings and the bulk runof-mine rock fill to prevent the migration of tailings. Within each embankment section, NAF rock fill will be used in portions below the phreatic surface to reduce the potential for development of acidic seepage. Due to the free draining nature of the rock fill embankments, the phreatic surface is anticipated to be very low and will be monitored by piezometers. The various embankment sections are shown on drawing D 6004. The initial starter embankment will be constructed with low permeability compacted clay and general fill. The placement and compaction of fill materials will be carried out in accordance with the technical specifications. Borrow areas will be developed within the TSF to provide some of this material (see drawing D-5116). The starter impoundment will store start-up supernatant water and tailings for one year of deposition. The general arrangement and cross-section details of the starter system are shown in drawings D 5101, D-5111 and D-5112. Load induced excess pore pressure may develop in the Cretaceous clay foundation and therefore the embankment stability is sensitive to the thickness of the clay. To account for this, the embankment perimeter was divided into a number of stability analysis sections, which reflect the thickness and/or absence of the clay. Each section was analysed and the required extent of a downstream toe buttress was determined. Buttresses will range from 50 m to 250 m wide resulting in downstream slopes ranging from 2.5:1 to 6.5:1 (horizontal to vertical). During operations, an observational approach will be used along with comprehensive monitoring of embankment foundations and test fills (including monitoring of pore pressure response and deformation), to confirm design assumptions and adjust construction rates and embankment slope angles, (see drawings D-5117 and D-5118). Permanent embankment deformations were estimated for the MCE using three methods: Newmark (1965), Hynes-Griffin and Franklin (1984) and Bray and Travsarou (2007). Deformations are predicted to range from 0.2 m to 1.4 m. This amount of movement is acceptable and will not cause an embankment failure or a release of tailings due to the width of the rock fill and filter zones within the embankment. 8.2 Tailings Production The life of mine plan during the design indicated that the total production of tailings would be in the order of 2.2 million tonnes during the first five years of mine life. The projected tailings production by year is presented in Table 3. Table 3 Projected Annual Tailings Production Projected Tailings Production 2012 2013 2014 2015 2016 Total Cell 1 (tonnes) 220,988 835,432 357,895 354,140 382,999 2,151,454 Page 15 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 9 Document Number: TSF-001 Rev: 2 OPERATION 9.1 Tailings Deposition The design tailings storage capacity of the TSF is 720 Mt of tailings (equivalent to 740 Mt processed ore) produced during the first 15 years of mine life. In addition, the TSF will be used to store 550 tpd of bottom ash and fly ash coming from the power plant. Tailings deposition between the two cells is as follows: Year 2012 to 2018: Deposition is in Cell 1 only; Year 2018: Deposition is in Cell 2 only; and Year 2019 to 2027: Deposition is in both cells, at a proportion of 32% to Cell 1 and 68% to Cell 2. 9.1.1 9.1.1.1 Tailing Pipeline and Pumping Operation of booster pump systems. Refer to: ..\6.22 TSF Training\05_Tailings_and_Reclaim_Water 9.1.1.2 Layout of header and spigot pipelines. Refer to ..\6.12. Tailings Storage Facility\6.12.2 TSF Operations\6.12.2.3 Deposition 9.1.2 Spigot Sequence Refer to ..\6.12. Tailings Storage Facility\6.12.2 TSF Operations\6.12.2.3 Deposition 9.1.2.1 Water reclaim operation Refer to: ..\6.22 TSF Training\05_Tailings_and_Reclaim_Water 9.1.2.2 Capturing “contact” water in the toe collection ditch. Refer to Site Spill Management Plan. 9.1.3 Raising Pipeline with Embankment Crest Refer to ..\6.12. Tailings Storage Facility\6.12.2 TSF Operations\6.12.2.3 Deposition 9.2 Water Management Refer to: ..\6.12. Tailings Storage Facility\6.12.2 TSF Operations\6.12.2.3 Deposition\111223 - Prelim Start-up Deposition Summary(for OT).pdf Refer to the Tailings Water Balance during startup located at: \\tuul\Data\Concentrator_ONON\6. Tailings\6.12. Tailings Storage Facility\6.12.2 TSF Operations\6.12.2.3 Deposition\090921 - Tailing Water Balance During Startup.xlsm Page 16 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 9.2.1 Document Number: TSF-001 Rev: 2 Storm/Flood Routing Storm water is routed around the TSF via the storm water drainage ditch. 9.2.2 Annual Construction Plan Referring to MTO, it is anticipated placing 835,000 tonnes of tailings into Cell 1 in 2013. Table 4 details construction completed to date and OT’s plans for the ongoing construction of the TSF Cells 1 and 2. Table 4 Annual Construction Plan Cell 1 Year 2012 Cell 1 Details Starter sub-cell D constructed from Sta. 0+000 to 0+415. Splitter dykes for sub-cells C, B and A constructed. Tailings placement in sub-cell D. Lifts 1 and 2 planned. Lifts 3 and 4 planned. Lifts 4 and 5 planned. Lifts 6 and 7 planned. 2013 2014 2015 2016 9.2.3 Seepage Collection Daily monitoring and observational approaches are expected to forewarn of potential adverse conditions that may be a result of embankment deformation. These include, but are not limited to, excessive tension cracking on the construction surface, visible slope deformation on the downstream side slope, and scarping on the construction surface, and monitoring of instrumentation. These kinds of observations would trigger geotechnical engineering support and increased measurement frequencies of the instrumentation. Severity triggers are not easily defined, and therefore any conditions or trends observed to be uncharacteristic would be handled with urgency to seek a better understanding of risk. Once the risk has been defined, appropriate steps can be engineered and implemented to rectify any nonconformance. 9.3 TSF Construction Components Refer to the construction specifications for start-up. The specifications include material types, gradation limits, placement and compaction is located at: \\tuul\Data\Concentrator_ONON\6. Tailings\6.12. Tailings Storage Facility\6.12.4 TSF Construction reports 9.4 Equipment Used for Construction Table 5 lists typical equipment employed in the construction of the TSF. Table 5 Equipment used for Construction Excavators Caterpillar 385 Liebherr 964 Caterpillar 365 Type 100 tonne-5 m Quantity 3 Status 1 Owned 70 tonne-3.5 m 3 2 Owned 70 tonne-3.5 m 3 1 Owned Page 17 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Liebherr 954 Caterpillar 330 Caterpillar 325 Document Number: TSF-001 55 tonne-3 m 3 30 tonne-2.4 m 25 tonne-2 m 3 3 Rev: 2 3 Owned 1 Owned 1 Owned Loaders 7m 3 2 Owned 5m 3 1 Owned Terex T60 60 tonne 16 Owned Caterpillar 773 55 tonne 5 Rental Caterpillar 769 40 tonne 2 Owned Caterpillar 16H 4 meter 2 Owned Komatsu GD655 3 meter 5 Owned 1 Owned 1 Owned 3 Owned 1 Rental 2 Owned Kawasaki 115ZV Caterpillar 976 Trucks Graders Dozers Komastsu 375A5 Caterpillar D8R 8.7 m 3 8.7 m 3 Liebherr 764 Caterpillar D8R Liebherr 754 Compactors Caterpillar CS563 10 tonne 2 Owned Bomag 611 15 tonne 1 Owned Caterpillar CS74 15 tonne 2 Rental Caterpillar 825 H 15 tonne 2 Owned 5 Rental Scrappers Caterpillar 621 9.5 17 m 3 Adverse Operating Conditions Potentially adverse conditions must be accounted for in the operation of the TSF. These conditions, along with mitigated measures of dealing with them, are as follows. High Rainfall Page 18 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Erosion control. Grade control and compaction of embankment during construction to seal lifts and prevent pooling of water. Compaction. May require drying out material prior to achieving compaction. Material requiring additional compaction effort will be moved to less critical areas of the TSF, for example placement in an area away from the ultimate embankment slope. High snow accumulation Removal prior to lift placements. Snow dumps will be sited to minimise any erosional impacts during thaw conditions. Freezing temperatures Location of placement. Placement in an area away from the ultimate embankment slope as compaction prior to freezing. Compaction – must be completed prior to the material freezing Tailings Characteristics (higher moisture) Location of placement. Placement area away from the ultimate tailings embankment Compaction. May require drying out material prior to achieving compaction. Material requiring additional compaction effort will be moved to less critical areas of the TSF, for example in an area away from the ultimate embankment slope. 9.6 Surface Water Management Run‐on surface water entering the TSF is managed through the construction of the freshwater diversion ditch. Surface water within the TSF is managed with the construction of reclaim pond and ensuring the tailings stack is graded to reduce the potential of surface erosion and direct any surface water to areas in which it can drain away from the facility. Any surface water that does enter the TSF is directed towards the reclaim pond where it is then pumped back to the Concentrator. 9.6.1 Flood Management The most important operational consideration is maintaining sufficient embankment freeboard to meet the design intent. Freeboard for the reclaim pond is 3m. Surface water will be managed by storage within the TSF as summarized below and in Table 6. 9.6.1.1 TSF Safety - Operations The TSF Cell 1 will store the 1 day 1,000 year return period event, which is 103 mm. The water volume will be reclaimed to the process plant over a period of 3 months (approximately 190 m3/hr); and The TSF will be able to safely store the Probable Maximum Precipitation (PMP) in the embankment by providing 3 mov. 9.6.1.2 Environmental Water Containment – Operations A seepage collection pond, located downstream of the TSF, will store the 100 yr event, 24 hour precipitation from the catchment area between the Cell 1 Embankment crest and Page 19 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 the seepage collection ditches, and the spillway for the pond will safely rout the 1,000 year peak flow. 9.6.1.3 Closure Safely manage the PMP with either: storage and routing of the flood or with direct flow over the embankments. Table 6 Summary of TSF Cell 1 Freeboard Cell 1 Stage Operations Closure Main portion 1 Ponded portion Main portion Ponded portion Splitter Dykes 9.7 Cell 1 Section Criteria Precipitation of 103mm (24hr100yr), and 2 m pond depth needed for barge. Safely route the PMP. Safely route the PMP. Main portion Ponded portion Freeboard (m) Height above Height above water (m) tailings (m) n/a 0.5 1 n/a n/a n/a 0 n/a n/a 0.5 0.5 n/a Environmental Protection It is every employee’s responsibility to report a suspected spill or uncontrolled release event to their supervisor. This includes suspicious flows of water out of the area, escaping tailings, any signs of turbid creek water, etc. The significance of multiple sets of eyes is that time plays a critical role in mitigating an emergency situation. The sooner appropriate persons can begin to correct a situation, the less likely it is that severe effects will follow. Given that the tailings are placed in a semi-saturated state and filter materials are a part of the design to restrict the tailings from transport, it is not likely that any tailings will be released from the TSF. Although unlikely, any tailings that are released from the TSF would eventually report to the seepage collection sump and returned to the reclaim pond. 9.8 Health, Safety, and Security The Oyu Tolgoi Mine is located in a remote setting approximately 500 km south of the capital city of Mongolia in the South Gobi Desert. Access either by land or by air. The mine site is not subject to general public traffic. Access roads from the Concentrator and Open Pit to and around the TSF are shown on Figure 1. 1 The ponded portion for the Starter Dam will include the northeast corner, extending to the centre of the East Dam. The ponded portion for operations will include the dam within 500 m of the reclaim pump barge. Page 20 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Established communication throughout the mine site and the TSF consists of a UHF radio and mobile phone. All personnel working at the TSF, including contractors, are to have an appropriate understanding of the TSF OMS manual and their respective roles and responsibilities. It is the role of the specific supervisor of the personnel to ensure this is the case. In addition to the general understanding of the OMS manual, it is the responsibility of all personnel involved in the operation of the TSF to be continually vigilant of changes reflecting facility performance. Anything observed to be outside of normal operating parameters, as outlined in this manual, are to be reported immediately to the Concentrator Control Room and Mine Control. The tailings materials themselves contain trace amounts of reagents added in the milling process. These reagents include, but may not be limited to. As a general precaution, it is recommended that any worker handling or coming into contact with the tailings wash their hands prior to ingesting any food. Further information regarding these reagents is available in the MSDS compilations found at the Concentrator and in the TSF office. Workplace safe operating procedures will be in place for those working in the area. 9.9 Reporting Any observations through the daily monitoring of the facility that identify significant change in the condition of the facility, or that the design criteria are not being achieved should be reported to the Superintendent Tailings Operations and Maintenance, Tailings Engineer, the Engineer of Record and Geotechnical Consultant, and the geotechnical consultant. This includes all components of the TSF. Changes to the ongoing operations of the TSF should be reported to the Tailings Engineer, Engineer of Record and Geotechnical Consultant and the geotechnical consultant. Any environmental changes to the TSF should be reported to the Environment department and the Superintendent Tailings Operations and Maintenance. 10 MAINTENANCE 10.1 Objective The objective of the maintenance program is to maintain the TSF in accordance with all the performance criteria, legislative requirements, Oyu Tolgoi company standards, and sound operating practices. Maintenance for the TSF is limited to the heavy equipment used for the ongoing construction and the TSF components themselves. Maintenance of the heavy equipment could consist of routine, predictive, and event‐driven maintenance and will be managed by the Infrastructure Mobile Equipment Superintendent. Maintenance for the TSF components is strictly event‐driven maintenance and will result from inspections completed by the Tailings Operations and Maintenance personal, Tailings Engineer, and the geotechnical consultant. 10.2 Maintenance Procedures Page 21 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 A preventive maintenance program is in place for the mobile and fixed plant used by Tailings Operations and Maintenance personnel at the TSF under the direction of the Mobile Maintenance Manager and Concentrator Maintenance Manager respectively. Event‐driven maintenance for the mobile and fixed plant equipment would be due to breakdowns or incidents. Whether a piece of equipment is down due to preventive, routine, or event‐driven maintenance, other equipment on site can be made available for use at the TSF as required. Event‐driven maintenance to the TSF civil components will be directed by the Superintendent TSF Construction under the consultation of the Tailings Engineer, Engineer of Record and Geotechnical Consultant and geotechnical consultant. The actual maintenance program completed will depend on the severity of the occurrence. Table 7 Routine Maintenance Requirements Tailings pipeline and valves Periodic per OEM Specification Reclaim barge Periodic per OEM Specification Toe collection pump houses Periodic per OEM Specification Monitoring equipment Periodic per OEM Specification 10.3 Documentation Record keeping and documentation of any TSF equipment maintenance is the responsibility of the TSF Planners. Event‐driven maintenance for a TSF Construction component is the responsibility of the Superintendent TSF Construction. It involves completing inspection reports and, depending on the severity of the event, may involve the Tailings Engineer and geotechnical consultant. Documentation of any maintenance completed will be used to assess the performance of the specific component and determine whether the design, operation, or surveillance of that component must be adjusted. 10.4 Reporting Reporting of any mobile or fixed plant equipment maintenance is limited to a specific request by the Superintendent Tailings Operations and Maintenance to the relevant Superintendents. Inspection reports and any other documentation regarding event driven maintenance for a TSF civil earthworks component should be submitted to the Tailings Engineer, Engineer of Record and Geotechnical Consultant and geotechnical consultant to determine whether any adjustments to the design, operation, or surveillance are required. 11 SURVEILLANCE 11.1 Objective Surveillance involves inspection and monitoring of the operation, structural integrity, and safety of the TSF, and must be consistent with the life cycle and regulatory requirements of the facility. Surveillance of the TSF consists of both routine and event‐driven activities. Key surveillance parameters and procedures must be identified for: Page 22 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Monitoring the operation, safety, and environmental performance of the TSF; Promptly identifying and evaluating deviations from expected behaviour that affect operation safety, structural integrity, and environmental performance of the facility; and Reporting significant observations for response. The TSF surveillance program will continue to evolve as the facility changes in design or performance criteria, site conditions and/or the operation it is accommodating. All personnel working at the TSF will be involved in surveillance as a routine part of daily activities, maintaining visual awareness of the facility in the course of their regular or routine duties, in addition to surveillance‐specific site engineering, instrument monitoring, analysis, inspection, periodic review and oversight. Regular inspections assisted by the eyes of all site personnel ensure continued integrity and performance of the facility. Outside consultants will also be on site periodically inspecting the facility as part of a regular program of expert review. 11.2 Instrumentation Piezometers Page 23 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 11.3 Document Number: TSF-001 Rev: 2 Responsibility A number of personnel conduct routine inspections of the TSF. The Tailings Engineer, or designated replacement, is assigned the responsibility of obtaining the monitoring information and preparing a monthly report for the Engineer of Record and Geotechnical Consultant and geotechnical consultant to review. 11.4 Surveillance Parameters Key parameters of surveillance are identified through identifying and describing potential failure modes of the dry storage TSF. Visual observations of the TSF can indicate potential failure modes such as: Surface – cracking, bulging, depressions, sink holes; Seepage – new seepage areas, changes in seepage areas; Turbid water in the natural drainages around or downstream of the facility; Water or tailings flowing down the stack indicating improper grading; and A failure or breach of a component of the facility. Routine monitoring for ensuring facility performance include: Checking for settlement or holes in embankment crest or benches; Checking for holes on the surface of the tailings indicating possible piping of material to outside; Measuring piezometer pore pressures in the foundation soils during operation; Measuring ground temperatures using cables in the foundation soils during operation; Page 24 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Surveying TSF components – displacements of waste rock shell or survey monuments; Water sampling – quality in surrounding and downstream areas; and Recording weather conditions. These parameters are further described in the following sections. 11.5 Surveillance Procedures Table 10 summarises surveillance requirements for the components of the TSF. These surveillance requirements are the licensed monitoring requirements and conditions regarding the tailings presented in Oyu Tolgoi’s Mining and Water Use licences. Table 8 TSF Operations Observations and Monitoring Work Plan (frequency) Year 1 - 3 Observation and Monitoring Units Frequency Weather and Climate o C average daily temperature daily kph average daily wind velocity daily mm rainfall / snow daily tpd Concentrator flows (automated) daily % solids (wt) thickener output (automated) l/sec quantity of makeup water daily ppm quality of makeup water (constituents) monthly % survey / measure at stakes monthly % solids take Marcy sample ppm observe, photograph and measure daily Oxide Material Properties tons Measure in field daily ROM Material Properties tons Measure in field daily Material Delivery tpd operational observations daily tpd quantity placed daily tons, % -200 quantity placed & % passing no. 200 sieve daily Tailings deposition Concentrator throughput Solids concentration - mill thickener Make-up water daily Embankment / Beach construction Beach slope angle Solids concentration - at TSF (spigot) Dust and Emissions Waste Rock Fine filter-B1 weekly Page 25 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Waste Rock General filter-B2 Waste Rock - Sedimentary C Sand and Gravel Filter - D Waste Rock - Controlled placement - F1 Waste Rock - General Fill F2 Non / Potentially-Acid Forming breakdown NAF/PAF material identification Document Number: TSF-001 tons, % -200 quantity placed & % passing no. 200 sieve tons quantity placed tons, % -200 tons quantity placed & % passing no. 200 sieve quantity placed / # passes of compaction equipment (trucks) tons quantity placed %S % sulfur in waste NAF/PAF Balance Rev: 2 daily daily daily daily daily daily Update with mine plan quarterly Oxide Material Properties %S Measure in field (blastholes) daily ROM Material Properties %S Measure in field (blastholes) daily column leach tests to assess ARD potential quarterly Leaching Cretaceous clay (Geotechnical) performance monitor and perform trial Measure in field / download DAS (data acquisition system) Kpa Piezometers Inclinometers Surface Survey monuments monthly cm or cm/day Measure in field cm Measure in field - GPS quarterly quarterly turbidity observe & sample daily % observe bi-monthly ppm / turbidity Process water constituents / turbidity meter daily Decant Performance Pond Clarity Subaqueous beach stability decant pond water quality Water Balance 3 m /time 3 m /day measure return water (pump) flows Update water balance calculations (spreadsheet) quarterly daily Surface Water Sampling toe ditch seepage ppm Environmental Constituents quarterly Other seepage l/day observe, sample as observed quarterly Groundwater Monitoring Page 26 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Groundwater sampling and analysis ppm operational monitoring bores ppm Monitor well network sampling (various constituents) pump well network (various constituents) Rev: 2 quarterly / semi-annual quarterly / semi-annual Notes: Indicates some form of automated acquisition system should be used. Automation possible 11.6 Adaptive Management Fundamental to successful adaptive management of the tailings production, handling and placement are triggers for management action. If the tailings handling and deposition is not meeting critical performance objectives according to specific conditions, the Superintendent Tailings Operations and Maintenance will be expected to follow Table 9 for appropriate corrective action. Close monitoring of the performance of the TSF will be critical in determining if and when action will be required. Table 9 Triggers and Actions under Adaptive Management for Tailings Management Monitored Item Triggers and Thresholds Action Inclinometers Acceleration of Movement Tailings Engineer will review existing inclinometer Data quarterly. (to be fitted) Tailings Engineer will read inclinometer and determine if tailings placement or construction plan requires modification. Monitoring and review will be increased to weekly until determined unnecessary (movement rates halt). Tailings Engineer will determine if additional instrumentation is required. Tailings Engineer will complete analysis of mitigated measures should abnormal results continue. Vibrating Wire Piezometers Varies by location – see geotechnical instrumentation drawings. Tailings Engineer will plot trends and review existing piezometer data monthly. Tailings Engineer will conduct a site visit and determine if tailings placement or construction plan requires modification. Monitoring and review will be increased to weekly or daily until determined unnecessary. Tailings Engineer will determine if additional instrumentation is required. Tailings Engineer will complete analysis of mitigated measures should abnormal results continue. Page 27 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Ground Temperature Cables Ambient Temperature < 0°C at XX m depth and greater. Document Number: TSF-001 Rev: 2 Tailings Engineer will review temperature data to identify frozen ground conditions, ice lenses, etc. Tailings Engineer will conduct a site visit and determine if tailings placement or construction (fill placement) requires modification. Tailings Engineer will determine if additional instrumentation, investigation or analysis is required. Tailings engineer will determine the suitability of new fill placed on frozen ground conditions Tailings Engineer will complete analysis of mitigated measures and/or determine whether recently placed frozen fill should be removed based on findings. Oyu Tolgoi to complete survey of area of interest to monitor any future displacement, settlement, if any. Beach Slope Measure average beach slope and determine variation from 1% design assumption. Tailings Engineer will record tailings levels on stakes and periodically survey beach slope to observe design conformance. Beach slopes impact freeboard and dyke raise requirements. Minor variations in between 1 % (+/-) slope will modify need for dyke raises. [Note: starter dam design incorporates beach slope variations from 0.7% to 1.5% with nominal slope of 1% used in design.] Flatter beach slopes (lower solids content) require more frequent east dyke raises. Steeper beach slopes will require deposition line to be raised. Survey Monuments Displacements between > 25 mm in any direction. Tailings Engineer will review survey data to evaluate whether frost related or slope related movement has occurred. Monitoring and review will be increased to bi-weekly until determined unnecessary. Oyu Tolgoi to complete survey of area of interest to monitor any future displacement, if any. Tailings Engineer will determine if tailings placement and/or construction plan requires modification. Tailings Engineer will determine if additional instrumentation is required. Survey Monuments Displacements greater than 25 mm in any direction Tailings Engineer will review existing piezometer, temperature, and survey data. Tailings Engineer will conduct a site visit and determine if tailings placement or construction plan requires modification. Monitoring and review will be increased to semi-weekly until determined unnecessary. Oyu Tolgoi to complete survey of area of interest to monitor any future displacement, if any. Page 28 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Tailings Engineer will determine if additional instrumentation is required. Tailings Engineer will complete analysis of mitigated measures should abnormal results continue. Tailings Material Solids Content If tailings are less than 58% solids by weight. Solids content variations in the tailings will impact beach slopes and hence impact freeboard requirements on both the U/S (west) and D/S (east) ends of the deposition area. Tailings engineer to survey beach slopes and plot beach slope trends over time. Identify freeboard and dike raise requirements due to varying tailings deposition density. Adjust construction sequence to maintain freeboard. Identify areas of wind erosion or dried tailings crust due to variation in beach slopes. Evaluate filter operations to determine methods to increase efficiency in collecting water from Concentrator slurry. Reclaim Pond Level Survey reclaim pond level. Survey reclaim pond and dyke level to assure that 1 m of freeboard is maintained before next planned dyke raise. [Freeboard may be measured relative to maximum operating level of decant barge at its current position.] Confirm that freeboard will be maintained over winter, when next dyke raise can be completed. Diversion Ditches Tailings Runoff Tailings Solids Presence of abnormal cracking, erosion or failure Report to Superintendent Tailings Operations and Maintenance, take corrective action as required. Visible turbidity in runoff or excessive erosion evidence Address runoff at source. ARD potential is indicated. Expand monitoring program. For diversion ditches, repair and re-establish flow lines immediately to prevent co-mingling of tailings and natural waters. Apply appropriate runoff, erosion or sediment control measures Identify locations of ARD (PAG-Potentially Acid Generating) tailings in impoundment and time periods over which PAG was placed. Conduct study of options to minimize acid generation. Pit and Borrow Sources (Construction Material) ARD potential is indicated. Tailings Surface Survey indicates >X m/season tailings Assure that PAG materials are not placed in areas designated NAG only (such as lowermost 3 m of embankment shells or near final embankment slopes) Change source material and use material without ARD potential Stop or adjust tailings placement in that area. Page 29 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Elevation placement. Document Number: TSF-001 Rev: 2 Identify freeboard and future dike raise requirements considering season and ability to raise dike. Engineer of Record and Geotechnical Consultant review topographic survey data and assess freeboard requirements. 11.7 Documentation Routine reporting of surveillance results is essential to provide time to make adjustments to existing systems or to initiate Emergency Response Plans. It is imperative that any unusual information (outliers) gathered from these undertakings be communicated to the Engineer of Record and Geotechnical Consultant, geotechnical or environmental consultant. Document control is vital to ensuring the ongoing performance of the facility. Table 10 identifies the overall responsibilities for surveillance record keeping. Table 10 TSF Surveillance Documentation Task Responsible Party Information Recipients Weekly Check Sheet Completed by Construction Engineer TSF Construction Superintendent – copy. Superintendent Tailings Operations and Maintenance – copy. Oyu Tolgoi Mine Engineering Server. Monthly Placement Asbuilt Completed by Construction Engineer. TSF Construction Superintendent – copy. Manager Mine Operations – copy. Manager Technical Services – copy. Oyu Tolgoi Mine Engineering Server. Engineer of Record and Geotechnical Consultant – copy. Instrumentation Data Completed by Construction Engineer. TSF Construction Superintendent – copy. Superintendent Tailings Operations and Maintenance – copy. Oyu Tolgoi Mine Engineering Server. Engineer of Record and Geotechnical Consultant - copy Construction Photographs Completed by Construction Engineer TSF Construction Superintendent – copy. Manager Mine Operations – copy. Manager Technical Services – copy. Oyu Tolgoi Mine Engineering Server. Acid Base Accounting (ABA) Testing. Completed by Open Pit Department TSF Construction Superintendent – copy. Manager Mine Operations – copy. Page 30 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Manager Technical Services – copy. Oyu Tolgoi Mine Engineering Server. Water Quality Monitoring Completed by Environmental Department TSF Construction Superintendent – copy. Superintendent TSF Operations and Maintenance – copy. Manager Mine Operations – copy. Manager Technical Services – copy. Manager Concentrator Operations – copy. Original reports located with Manager of Regulatory and Corporate Affairs. 11.8 Reporting Observation of any unusual occurrence should be reported immediately to the TMT. Unusual occurrences include but are not limited to the following: Triggers and Thresholds outlined in Table 9; Any seismic event; Settlement, cracks or slumping of the tailings stack; Slope failure of any of the slopes; Abnormal seepage from any of the slopes; Increased or high turbidity flow from the finger drains; and Damage to any component of the TSF. All reports are to be maintained by the Superintendent Tailings Operations and Maintenance and filed in a suitable format and location (business readiness e-room and RTBS) for easy access by authorised mine personnel, and for review by government agencies. Annual performance reviews will be copied to the regulatory agencies. The requirements of the consulting geotechnical engineer, other departments, or governmental agencies may dictate certain items that require inspection, monitoring, or reporting. 12 EMERGENCY PLANNING AND RESPONSE 12.1 OT Emergency Procedures. Refer to: OT Emergency Procedure. The mine site has established procedures and response plans detailing in the following documents: Oyu Tolgoi Spill Contingency Plan. MSDS documentation for any material used within the TSF. These documents provide the relevant guidance on actions to be taken in case of an emergency. They also provide notification procedures. Page 31 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 12.2 Document Number: TSF-001 Rev: 2 TSF Emergency Procedures Daily visual and routine instrumentation monitoring programs outlined in Tables 8 and 9 are expected to forewarn of potential adverse conditions to the TSF. Triggers and Thresholds presented in Table 9 must be adhered to and reported on as outlined. The TSF has been designed to maintain its structural integrity throughout its operational life; however, a number of conditions can affect the performance of the TSF. Refer to: ..\6.12. Tailings Storage Facility\6.12.1 TSF Safety\Oyu Tolgoi - Checklist - TSF Safety Emergency Plan - 24 Jun 11.docx <Refer to: ..\6.14. Compliance and SWPs\TSF Embankment\TSF Embankment Failure Prevention - 9 Jun 12.docx 12.3 Environmental Emergencies Environmental emergencies of various natures and their specific response procedures are outlined in the Oyu Tolgoi Spill Contingency Plan. This document includes immediate response procedures and follow up and notification measures appropriate to the particular nature of the emergency. Refer to: OT Emergency Procedure. 12.4 Key Contacts Table 11 TSF Key Contacts Position Personnel and Contact Information Superintendent Tailings Operations and Maintenance Clem Turner Superintendent TSF Construction Scott Ingram Superintendent Concentrator Operations Jody Squires Tailings Engineer Odkhuu Tsogtbaatar Supervisor TSF Construction Munkh-Erdene Amarsanaa; Bat-Amgalan Sangaa; Nasanbuyan Tserenbat; Supervisor TSF Operations and Maintenance Tsogjavkhlan Sodnomdarjaa Superintendent Safety – Concentrator Bat-Erdene Dambadarjaa Superintendent Safety – Open Pit Jennifer Sutcliffe Manager Mine Operations Morris Dzus Manager Technical Services Binsar Sirait Manager Concentrator Operations Adrian Zarantonello Page 32 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 12.4.1 Engineer of Record and Geotechnical Consultant and Geotechnical Consultant Position Personnel and Contact Information Principal Adviser – Geotechnical Joergen Pilz Engineer of Record and Geotechnical Consultant, KCB Howard Plewes Design Authority Project Manager, KCB Pam Fines 12.4.2 Local Authorities Position Personnel and Contact Information National Compliance Superintendent Environment Erdenetuya Ganbold Superintendent Environment Bayarjargal Batsukh Superintendent Safety - Concentrator Bat-Erdene Dambadarjaa 13 CLOSURE TSF structures will be stable on closure and shall not impose a risk to public health and safety, or the environment. The TSF will be closed as a dry facility. Consolidation and drain-down of the tailings will minimize geotechnical risk. Dust control could potentially require the placement of a layer of rock-fill over the tailings, or potentially rely on the crusted tailings to control dust. Test plots will be carried out during operations to confirm the basis for design of the cover. A low permeability cover will be placed over the PAF waste rock to minimize infiltration of surface water. All natural surface water flow will be directed away from contact with the PAF waste rock to minimize the potential for leaching and “contaminating” surface runoff. Test plots will be carried out during operations to confirm the basis for design of the cover. Major precipitation events (Probable Maximum Precipitation) will be either be stored on the surface and evaporated, or safely routed down the face of the dam. The fate, transport, and impact of seepage will be assessed; short and, if required, long term measures for collection and evaporation will be developed and implemented. 14 REFERENCES AND RELATED DOCUMENTS Page 33 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 Name Location Legal and Other Requirements Drawings issued for construction SSIA and GASI Certification File Server General (D-510x) D-5101 (A2MW-4200-10Z-401) – Site General Arrangement. D-5111 (A2MW-4200-10Z-402) – Starter Embankment Plan and Detail. D-5112 (A2MW-4200-10Z-403) – Starter Embankment Sections and Detail. D-5113 (A2MW-4200-10Z-404) – Reclaim Area Plan. D-5114 (A2MW-4200-10Z-405) – Reclaim Area Sections. D-5115 (A2MW-4200-10Z-406) – Clay Liner Plan and Sections. D-5116 (A2MW-4200-10Z-407) – Borrow Sources and Excavation Plan and Detail. D-5117 (A2MW-4200-10Z-408) – Embankment Instrumentation and Ground Water Monitoring Plan. D-5118 (A2MW-4200-10Z-409) – Embankment Instrumentation Sections (Sheet 1 of 2). D-5118 (A2MW-4200-10Z-424) – Embankment Instrumentation Sections (Sheet 2 of 2). D-5121 (A2MW-4200-10Z-410) – Water Management Plan. D-5122 (A2MW-4200-10Z-411) – Toe Collection Ditches – Profiles and Sections. D-5123 (A2MW-4200-10Z-412) – Diversion Ditch – Profile, Sections and Detail. D-5124 (A2MW-4200-10Z-413) – East Toe Collection Dyke – Plan and Sections. D-5125 (A2MW-4200-10Z-414) – East Toe Collection System – Plan and Detail. D-5126 (A2MW-4200-10Z-415) – East Toe Collection System – Concrete Sump Details. D-6001 (A2MW-4200-10Z-416) – Site Plan. D-6002 (A2MW-4200-10Z-417) – General Ultimate Arrangement – Year 15. D-6003 (A2MW-4200-10Z-418) – Site Investigation Plan. D-6004 (A2MW-4200-10Z-419) – Ultimate Embankment (Year 15) – Plan and Sections. D-6005 (A2MW-4200-10Z-420) – Water Reclaim – Layout and Sections at Year 5. D-6006 (A2MW-4200-10Z-421) – Toe and Diversion Ditches – Ultimate. D-6007 (A2MW-4200-10Z-422) – Cell 2 Starter Embankment Plan (Year 5). D-6008 (A2MW-4200-10Z-423) – Closure Plan. File Server Canadian Dam Association Dam Safety Guidelines 2007. File Server TSF Starter Embankment (D-511x) Water Management Structures (D-512x) Information Drawings (D600x) Reference File Server File Server File Server Forms, Checklists, Page 34 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Permits, Templates Records Document Number: TSF-001 TSF Red Book, Construction Reports, Field Instructions and Field Memos. Rev: 2 TSF Engineer Communication / Training TABLES Table 1 Designated Personnel for TMT Table 2 Anticipated Tailings Production Table 3 Projected Annual Tailings Production Table 4 Annual Construction Plan Cell 1 Table 5 Equipment used for Construction Table 6 Summary of TSF Cell 1 Freeboard Table 7 Routine Maintenance Requirements Table 8 TSF Operations Observations and Monitoring Work Plan (frequency) Table 9 Triggers and Actions under Adaptive Management for Tailings Management Table 10 TSF Surveillance Documentation Table 11 TSF Key Contacts FIGURES Figure 1 Flowchart TSF Change Management Process. Figure 2 Site Plan. Figure 3 TSF Instrumentation. Figure 4 Surface Drainage Sub-catchments. APPENDICES Appendix A Geotechnical Design Report – Tailings Storage Facility, Oyu Tolgoi Mine, Mongolia Starter Embankment construction specifications. Embankment construction specifications. MTOs for Life of Mine. Equipment fleet and haulage. NAF/PAF delineation. OT closure plan. OT Risk Assessment and Register. ..\6.14. Compliance and SWPs\1. Safety General\Risk Assessment - Tailings Storage Facility - Operations and Maintenance - 7 Jun 12.xlsx 15 DOCUMENT CONTROL File Name Description Original Author(s) Creation Date Oyu Tolgoi – TSF Operations, Maintenance and Surveillance Manual Guidance document for TSF Operations, Maintenance and Surveillance Clem Turner 30 July 2011 Page 35 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Approved By Approval Date Change Record Number Document Number: TSF-001 Rev: 2 Chelvan Veloo 20 June 2012 Rev 2.0 Revision Revision Date Author(s) Approved By Revision Notes .1 .2 1 2 30 July 2011 17 June 2012 20 June 2012 6 May 2013 Clem Turner Clem Turner Clem Turner Clem Turner Chelvan Veloo Chelvan Veloo Chelvan Veloo Andrew Millar Draft Review release Approved Roles and responsibilities updated to reflect organisational structure change. TSF Construction owner is GM Open Pit. TSF Operations and Maintenance owner is GM Concentrator. Page 36 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15 OYU TOLGOI LLC TSF – Operations, Maintenance and Surveillance Effective Date: 24 June 2013 Document Number: TSF-001 Rev: 2 16 APPENDIX A – Page 37 of 37 UNCONTROLLED COPY WHEN PRINTED. REFER TO PROSPECT FOR LATEST VERSION PRINTED DATE: 2013-11-15
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